(there are some 20 other locations in the Midwest - and 1 in AR)
Dog n Suds started in Champaign, Illinois, in 1953, and had some 600 (!) locations in 38 states and Canada n the mid 1970s! Nowadays they are back to some 20 locations in the Midwest. They are famous for their "coney dogs" and root beers. To be honest, I don't understand what attracts people to eating in their car... it is inconvenient and messy.
I ordered a Texas Burger basket and a strawberry shake (together just over $10). The burger is "made using two burger patties, 1 1/2 buns (One top, one middle, and one bottom), a slice of cheese on the top burger, lettuce and the Dog N Suds secret sauce on the middle bun, and Coney sauce on the bottom bun" (Wiki); I had it without cheese). It tasted ok, but overal a bit spongie. I would have preferred only the Coney sauce. The fries were uneventful, while the shake was big and sweet.
VERDICT: 72/100
Dog n Suds is a relic of the past, which might do great dogs and roots, but their burgers, fries and shakes are not exceptional.